// This is free and unencumbered software released into the public domain.
// See LICENSE.md for more information.

/**
 * @fileoverview Global |this| required for resolving indexes in node.
 * @suppress {globalThis}
 */
;(function (global) {
    "use strict"

    // If we're in node require encoding-indexes and attach it to the global.
    if (typeof module !== "undefined" && module.exports && !global["encoding-indexes"]) {
        global["encoding-indexes"] = require("./encoding-indexes.js")["encoding-indexes"]
    }

    //
    // Utilities
    //

    /**
     * @param {number} a The number to test.
     * @param {number} min The minimum value in the range, inclusive.
     * @param {number} max The maximum value in the range, inclusive.
     * @return {boolean} True if a >= min and a <= max.
     */
    function inRange(a, min, max) {
        return min <= a && a <= max
    }

    /**
     * @param {!Array.<*>} array The array to check.
     * @param {*} item The item to look for in the array.
     * @return {boolean} True if the item appears in the array.
     */
    function includes(array, item) {
        return array.indexOf(item) !== -1
    }

    var floor = Math.floor

    /**
     * @param {*} o
     * @return {Object}
     */
    function ToDictionary(o) {
        if (o === undefined) return {}
        if (o === Object(o)) return o
        throw TypeError("Could not convert argument to dictionary")
    }

    /**
     * @param {string} string Input string of UTF-16 code units.
     * @return {!Array.<number>} Code points.
     */
    function stringToCodePoints(string) {
        // https://heycam.github.io/webidl/#dfn-obtain-unicode

        // 1. Let S be the DOMString value.
        var s = String(string)

        // 2. Let n be the length of S.
        var n = s.length

        // 3. Initialize i to 0.
        var i = 0

        // 4. Initialize U to be an empty sequence of Unicode characters.
        var u = []

        // 5. While i < n:
        while (i < n) {
            // 1. Let c be the code unit in S at index i.
            var c = s.charCodeAt(i)

            // 2. Depending on the value of c:

            // c < 0xD800 or c > 0xDFFF
            if (c < 0xd800 || c > 0xdfff) {
                // Append to U the Unicode character with code point c.
                u.push(c)
            }

            // 0xDC00 ≤ c ≤ 0xDFFF
            else if (0xdc00 <= c && c <= 0xdfff) {
                // Append to U a U+FFFD REPLACEMENT CHARACTER.
                u.push(0xfffd)
            }

            // 0xD800 ≤ c ≤ 0xDBFF
            else if (0xd800 <= c && c <= 0xdbff) {
                // 1. If i = n−1, then append to U a U+FFFD REPLACEMENT
                // CHARACTER.
                if (i === n - 1) {
                    u.push(0xfffd)
                }
                // 2. Otherwise, i < n−1:
                else {
                    // 1. Let d be the code unit in S at index i+1.
                    var d = s.charCodeAt(i + 1)

                    // 2. If 0xDC00 ≤ d ≤ 0xDFFF, then:
                    if (0xdc00 <= d && d <= 0xdfff) {
                        // 1. Let a be c & 0x3FF.
                        var a = c & 0x3ff

                        // 2. Let b be d & 0x3FF.
                        var b = d & 0x3ff

                        // 3. Append to U the Unicode character with code point
                        // 2^16+2^10*a+b.
                        u.push(0x10000 + (a << 10) + b)

                        // 4. Set i to i+1.
                        i += 1
                    }

                    // 3. Otherwise, d < 0xDC00 or d > 0xDFFF. Append to U a
                    // U+FFFD REPLACEMENT CHARACTER.
                    else {
                        u.push(0xfffd)
                    }
                }
            }

            // 3. Set i to i+1.
            i += 1
        }

        // 6. Return U.
        return u
    }

    /**
     * @param {!Array.<number>} code_points Array of code points.
     * @return {string} string String of UTF-16 code units.
     */
    function codePointsToString(code_points) {
        var s = ""
        for (var i = 0; i < code_points.length; ++i) {
            var cp = code_points[i]
            if (cp <= 0xffff) {
                s += String.fromCharCode(cp)
            } else {
                cp -= 0x10000
                s += String.fromCharCode((cp >> 10) + 0xd800, (cp & 0x3ff) + 0xdc00)
            }
        }
        return s
    }

    //
    // Implementation of Encoding specification
    // https://encoding.spec.whatwg.org/
    //

    //
    // 4. Terminology
    //

    /**
     * An ASCII byte is a byte in the range 0x00 to 0x7F, inclusive.
     * @param {number} a The number to test.
     * @return {boolean} True if a is in the range 0x00 to 0x7F, inclusive.
     */
    function isASCIIByte(a) {
        return 0x00 <= a && a <= 0x7f
    }

    /**
     * An ASCII code point is a code point in the range U+0000 to
     * U+007F, inclusive.
     */
    var isASCIICodePoint = isASCIIByte

    /**
     * End-of-stream is a special token that signifies no more tokens
     * are in the stream.
     * @const
     */ var end_of_stream = -1

    /**
     * A stream represents an ordered sequence of tokens.
     *
     * @constructor
     * @param {!(Array.<number>|Uint8Array)} tokens Array of tokens that provide
     * the stream.
     */
    function Stream(tokens) {
        /** @type {!Array.<number>} */
        this.tokens = [].slice.call(tokens)
        // Reversed as push/pop is more efficient than shift/unshift.
        this.tokens.reverse()
    }

    Stream.prototype = {
        /**
         * @return {boolean} True if end-of-stream has been hit.
         */
        endOfStream: function () {
            return !this.tokens.length
        },

        /**
         * When a token is read from a stream, the first token in the
         * stream must be returned and subsequently removed, and
         * end-of-stream must be returned otherwise.
         *
         * @return {number} Get the next token from the stream, or
         * end_of_stream.
         */
        read: function () {
            if (!this.tokens.length) return end_of_stream
            return this.tokens.pop()
        },

        /**
         * When one or more tokens are prepended to a stream, those tokens
         * must be inserted, in given order, before the first token in the
         * stream.
         *
         * @param {(number|!Array.<number>)} token The token(s) to prepend to the
         * stream.
         */
        prepend: function (token) {
            if (Array.isArray(token)) {
                var tokens = /**@type {!Array.<number>}*/ (token)
                while (tokens.length) this.tokens.push(tokens.pop())
            } else {
                this.tokens.push(token)
            }
        },

        /**
         * When one or more tokens are pushed to a stream, those tokens
         * must be inserted, in given order, after the last token in the
         * stream.
         *
         * @param {(number|!Array.<number>)} token The tokens(s) to push to the
         * stream.
         */
        push: function (token) {
            if (Array.isArray(token)) {
                var tokens = /**@type {!Array.<number>}*/ (token)
                while (tokens.length) this.tokens.unshift(tokens.shift())
            } else {
                this.tokens.unshift(token)
            }
        },
    }

    //
    // 5. Encodings
    //

    // 5.1 Encoders and decoders

    /** @const */
    var finished = -1

    /**
     * @param {boolean} fatal If true, decoding errors raise an exception.
     * @param {number=} opt_code_point Override the standard fallback code point.
     * @return {number} The code point to insert on a decoding error.
     */
    function decoderError(fatal, opt_code_point) {
        if (fatal) throw TypeError("Decoder error")
        return opt_code_point || 0xfffd
    }

    /**
     * @param {number} code_point The code point that could not be encoded.
     * @return {number} Always throws, no value is actually returned.
     */
    function encoderError(code_point) {
        throw TypeError("The code point " + code_point + " could not be encoded.")
    }

    /** @interface */
    function Decoder() {}
    Decoder.prototype = {
        /**
         * @param {Stream} stream The stream of bytes being decoded.
         * @param {number} bite The next byte read from the stream.
         * @return {?(number|!Array.<number>)} The next code point(s)
         *     decoded, or null if not enough data exists in the input
         *     stream to decode a complete code point, or |finished|.
         */
        handler: function (stream, bite) {},
    }

    /** @interface */
    function Encoder() {}
    Encoder.prototype = {
        /**
         * @param {Stream} stream The stream of code points being encoded.
         * @param {number} code_point Next code point read from the stream.
         * @return {(number|!Array.<number>)} Byte(s) to emit, or |finished|.
         */
        handler: function (stream, code_point) {},
    }

    // 5.2 Names and labels

    // TODO: Define @typedef for Encoding: {name:string,labels:Array.<string>}
    // https://github.com/google/closure-compiler/issues/247

    /**
     * @param {string} label The encoding label.
     * @return {?{name:string,labels:Array.<string>}}
     */
    function getEncoding(label) {
        // 1. Remove any leading and trailing ASCII whitespace from label.
        label = String(label).trim().toLowerCase()

        // 2. If label is an ASCII case-insensitive match for any of the
        // labels listed in the table below, return the corresponding
        // encoding, and failure otherwise.
        if (Object.prototype.hasOwnProperty.call(label_to_encoding, label)) {
            return label_to_encoding[label]
        }
        return null
    }

    /**
     * Encodings table: https://encoding.spec.whatwg.org/encodings.json
     * @const
     * @type {!Array.<{
     *          heading: string,
     *          encodings: Array.<{name:string,labels:Array.<string>}>
     *        }>}
     */
    var encodings = [
        {
            encodings: [
                {
                    labels: ["unicode-1-1-utf-8", "utf-8", "utf8"],
                    name: "UTF-8",
                },
            ],
            heading: "The Encoding",
        },
        {
            encodings: [
                {
                    labels: ["866", "cp866", "csibm866", "ibm866"],
                    name: "IBM866",
                },
                {
                    labels: [
                        "csisolatin2",
                        "iso-8859-2",
                        "iso-ir-101",
                        "iso8859-2",
                        "iso88592",
                        "iso_8859-2",
                        "iso_8859-2:1987",
                        "l2",
                        "latin2",
                    ],
                    name: "ISO-8859-2",
                },
                {
                    labels: [
                        "csisolatin3",
                        "iso-8859-3",
                        "iso-ir-109",
                        "iso8859-3",
                        "iso88593",
                        "iso_8859-3",
                        "iso_8859-3:1988",
                        "l3",
                        "latin3",
                    ],
                    name: "ISO-8859-3",
                },
                {
                    labels: [
                        "csisolatin4",
                        "iso-8859-4",
                        "iso-ir-110",
                        "iso8859-4",
                        "iso88594",
                        "iso_8859-4",
                        "iso_8859-4:1988",
                        "l4",
                        "latin4",
                    ],
                    name: "ISO-8859-4",
                },
                {
                    labels: [
                        "csisolatincyrillic",
                        "cyrillic",
                        "iso-8859-5",
                        "iso-ir-144",
                        "iso8859-5",
                        "iso88595",
                        "iso_8859-5",
                        "iso_8859-5:1988",
                    ],
                    name: "ISO-8859-5",
                },
                {
                    labels: [
                        "arabic",
                        "asmo-708",
                        "csiso88596e",
                        "csiso88596i",
                        "csisolatinarabic",
                        "ecma-114",
                        "iso-8859-6",
                        "iso-8859-6-e",
                        "iso-8859-6-i",
                        "iso-ir-127",
                        "iso8859-6",
                        "iso88596",
                        "iso_8859-6",
                        "iso_8859-6:1987",
                    ],
                    name: "ISO-8859-6",
                },
                {
                    labels: [
                        "csisolatingreek",
                        "ecma-118",
                        "elot_928",
                        "greek",
                        "greek8",
                        "iso-8859-7",
                        "iso-ir-126",
                        "iso8859-7",
                        "iso88597",
                        "iso_8859-7",
                        "iso_8859-7:1987",
                        "sun_eu_greek",
                    ],
                    name: "ISO-8859-7",
                },
                {
                    labels: [
                        "csiso88598e",
                        "csisolatinhebrew",
                        "hebrew",
                        "iso-8859-8",
                        "iso-8859-8-e",
                        "iso-ir-138",
                        "iso8859-8",
                        "iso88598",
                        "iso_8859-8",
                        "iso_8859-8:1988",
                        "visual",
                    ],
                    name: "ISO-8859-8",
                },
                {
                    labels: ["csiso88598i", "iso-8859-8-i", "logical"],
                    name: "ISO-8859-8-I",
                },
                {
                    labels: ["csisolatin6", "iso-8859-10", "iso-ir-157", "iso8859-10", "iso885910", "l6", "latin6"],
                    name: "ISO-8859-10",
                },
                {
                    labels: ["iso-8859-13", "iso8859-13", "iso885913"],
                    name: "ISO-8859-13",
                },
                {
                    labels: ["iso-8859-14", "iso8859-14", "iso885914"],
                    name: "ISO-8859-14",
                },
                {
                    labels: ["csisolatin9", "iso-8859-15", "iso8859-15", "iso885915", "iso_8859-15", "l9"],
                    name: "ISO-8859-15",
                },
                {
                    labels: ["iso-8859-16"],
                    name: "ISO-8859-16",
                },
                {
                    labels: ["cskoi8r", "koi", "koi8", "koi8-r", "koi8_r"],
                    name: "KOI8-R",
                },
                {
                    labels: ["koi8-ru", "koi8-u"],
                    name: "KOI8-U",
                },
                {
                    labels: ["csmacintosh", "mac", "macintosh", "x-mac-roman"],
                    name: "macintosh",
                },
                {
                    labels: ["dos-874", "iso-8859-11", "iso8859-11", "iso885911", "tis-620", "windows-874"],
                    name: "windows-874",
                },
                {
                    labels: ["cp1250", "windows-1250", "x-cp1250"],
                    name: "windows-1250",
                },
                {
                    labels: ["cp1251", "windows-1251", "x-cp1251"],
                    name: "windows-1251",
                },
                {
                    labels: [
                        "ansi_x3.4-1968",
                        "ascii",
                        "cp1252",
                        "cp819",
                        "csisolatin1",
                        "ibm819",
                        "iso-8859-1",
                        "iso-ir-100",
                        "iso8859-1",
                        "iso88591",
                        "iso_8859-1",
                        "iso_8859-1:1987",
                        "l1",
                        "latin1",
                        "us-ascii",
                        "windows-1252",
                        "x-cp1252",
                    ],
                    name: "windows-1252",
                },
                {
                    labels: ["cp1253", "windows-1253", "x-cp1253"],
                    name: "windows-1253",
                },
                {
                    labels: [
                        "cp1254",
                        "csisolatin5",
                        "iso-8859-9",
                        "iso-ir-148",
                        "iso8859-9",
                        "iso88599",
                        "iso_8859-9",
                        "iso_8859-9:1989",
                        "l5",
                        "latin5",
                        "windows-1254",
                        "x-cp1254",
                    ],
                    name: "windows-1254",
                },
                {
                    labels: ["cp1255", "windows-1255", "x-cp1255"],
                    name: "windows-1255",
                },
                {
                    labels: ["cp1256", "windows-1256", "x-cp1256"],
                    name: "windows-1256",
                },
                {
                    labels: ["cp1257", "windows-1257", "x-cp1257"],
                    name: "windows-1257",
                },
                {
                    labels: ["cp1258", "windows-1258", "x-cp1258"],
                    name: "windows-1258",
                },
                {
                    labels: ["x-mac-cyrillic", "x-mac-ukrainian"],
                    name: "x-mac-cyrillic",
                },
            ],
            heading: "Legacy single-byte encodings",
        },
        {
            encodings: [
                {
                    labels: [
                        "chinese",
                        "csgb2312",
                        "csiso58gb231280",
                        "gb2312",
                        "gb_2312",
                        "gb_2312-80",
                        "gbk",
                        "iso-ir-58",
                        "x-gbk",
                    ],
                    name: "GBK",
                },
                {
                    labels: ["gb18030"],
                    name: "gb18030",
                },
            ],
            heading: "Legacy multi-byte Chinese (simplified) encodings",
        },
        {
            encodings: [
                {
                    labels: ["big5", "big5-hkscs", "cn-big5", "csbig5", "x-x-big5"],
                    name: "Big5",
                },
            ],
            heading: "Legacy multi-byte Chinese (traditional) encodings",
        },
        {
            encodings: [
                {
                    labels: ["cseucpkdfmtjapanese", "euc-jp", "x-euc-jp"],
                    name: "EUC-JP",
                },
                {
                    labels: ["csiso2022jp", "iso-2022-jp"],
                    name: "ISO-2022-JP",
                },
                {
                    labels: [
                        "csshiftjis",
                        "ms932",
                        "ms_kanji",
                        "shift-jis",
                        "shift_jis",
                        "sjis",
                        "windows-31j",
                        "x-sjis",
                    ],
                    name: "Shift_JIS",
                },
            ],
            heading: "Legacy multi-byte Japanese encodings",
        },
        {
            encodings: [
                {
                    labels: [
                        "cseuckr",
                        "csksc56011987",
                        "euc-kr",
                        "iso-ir-149",
                        "korean",
                        "ks_c_5601-1987",
                        "ks_c_5601-1989",
                        "ksc5601",
                        "ksc_5601",
                        "windows-949",
                    ],
                    name: "EUC-KR",
                },
            ],
            heading: "Legacy multi-byte Korean encodings",
        },
        {
            encodings: [
                {
                    labels: ["csiso2022kr", "hz-gb-2312", "iso-2022-cn", "iso-2022-cn-ext", "iso-2022-kr"],
                    name: "replacement",
                },
                {
                    labels: ["utf-16be"],
                    name: "UTF-16BE",
                },
                {
                    labels: ["utf-16", "utf-16le"],
                    name: "UTF-16LE",
                },
                {
                    labels: ["x-user-defined"],
                    name: "x-user-defined",
                },
            ],
            heading: "Legacy miscellaneous encodings",
        },
    ]

    // Label to encoding registry.
    /** @type {Object.<string,{name:string,labels:Array.<string>}>} */
    var label_to_encoding = {}
    encodings.forEach(function (category) {
        category.encodings.forEach(function (encoding) {
            encoding.labels.forEach(function (label) {
                label_to_encoding[label] = encoding
            })
        })
    })

    // Registry of of encoder/decoder factories, by encoding name.
    /** @type {Object.<string, function({fatal:boolean}): Encoder>} */
    var encoders = {}
    /** @type {Object.<string, function({fatal:boolean}): Decoder>} */
    var decoders = {}

    //
    // 6. Indexes
    //

    /**
     * @param {number} pointer The |pointer| to search for.
     * @param {(!Array.<?number>|undefined)} index The |index| to search within.
     * @return {?number} The code point corresponding to |pointer| in |index|,
     *     or null if |code point| is not in |index|.
     */
    function indexCodePointFor(pointer, index) {
        if (!index) return null
        return index[pointer] || null
    }

    /**
     * @param {number} code_point The |code point| to search for.
     * @param {!Array.<?number>} index The |index| to search within.
     * @return {?number} The first pointer corresponding to |code point| in
     *     |index|, or null if |code point| is not in |index|.
     */
    function indexPointerFor(code_point, index) {
        var pointer = index.indexOf(code_point)
        return pointer === -1 ? null : pointer
    }

    /**
     * @param {string} name Name of the index.
     * @return {(!Array.<number>|!Array.<Array.<number>>)}
     *  */
    function index(name) {
        if (!("encoding-indexes" in global)) {
            throw Error("Indexes missing." + " Did you forget to include encoding-indexes.js first?")
        }
        return global["encoding-indexes"][name]
    }

    /**
     * @param {number} pointer The |pointer| to search for in the gb18030 index.
     * @return {?number} The code point corresponding to |pointer| in |index|,
     *     or null if |code point| is not in the gb18030 index.
     */
    function indexGB18030RangesCodePointFor(pointer) {
        // 1. If pointer is greater than 39419 and less than 189000, or
        // pointer is greater than 1237575, return null.
        if ((pointer > 39419 && pointer < 189000) || pointer > 1237575) return null

        // 2. If pointer is 7457, return code point U+E7C7.
        if (pointer === 7457) return 0xe7c7

        // 3. Let offset be the last pointer in index gb18030 ranges that
        // is equal to or less than pointer and let code point offset be
        // its corresponding code point.
        var offset = 0
        var code_point_offset = 0
        var idx = index("gb18030-ranges")
        var i
        for (i = 0; i < idx.length; ++i) {
            /** @type {!Array.<number>} */
            var entry = idx[i]
            if (entry[0] <= pointer) {
                offset = entry[0]
                code_point_offset = entry[1]
            } else {
                break
            }
        }

        // 4. Return a code point whose value is code point offset +
        // pointer − offset.
        return code_point_offset + pointer - offset
    }

    /**
     * @param {number} code_point The |code point| to locate in the gb18030 index.
     * @return {number} The first pointer corresponding to |code point| in the
     *     gb18030 index.
     */
    function indexGB18030RangesPointerFor(code_point) {
        // 1. If code point is U+E7C7, return pointer 7457.
        if (code_point === 0xe7c7) return 7457

        // 2. Let offset be the last code point in index gb18030 ranges
        // that is equal to or less than code point and let pointer offset
        // be its corresponding pointer.
        var offset = 0
        var pointer_offset = 0
        var idx = index("gb18030-ranges")
        var i
        for (i = 0; i < idx.length; ++i) {
            /** @type {!Array.<number>} */
            var entry = idx[i]
            if (entry[1] <= code_point) {
                offset = entry[1]
                pointer_offset = entry[0]
            } else {
                break
            }
        }

        // 3. Return a pointer whose value is pointer offset + code point
        // − offset.
        return pointer_offset + code_point - offset
    }

    /**
     * @param {number} code_point The |code_point| to search for in the Shift_JIS
     *     index.
     * @return {?number} The code point corresponding to |pointer| in |index|,
     *     or null if |code point| is not in the Shift_JIS index.
     */
    function indexShiftJISPointerFor(code_point) {
        // 1. Let index be index jis0208 excluding all entries whose
        // pointer is in the range 8272 to 8835, inclusive.
        shift_jis_index =
            shift_jis_index ||
            index("jis0208").map(function (code_point, pointer) {
                return inRange(pointer, 8272, 8835) ? null : code_point
            })
        var index_ = shift_jis_index

        // 2. Return the index pointer for code point in index.
        return index_.indexOf(code_point)
    }
    var shift_jis_index

    /**
     * @param {number} code_point The |code_point| to search for in the big5
     *     index.
     * @return {?number} The code point corresponding to |pointer| in |index|,
     *     or null if |code point| is not in the big5 index.
     */
    function indexBig5PointerFor(code_point) {
        // 1. Let index be index Big5 excluding all entries whose pointer
        big5_index_no_hkscs =
            big5_index_no_hkscs ||
            index("big5").map(function (code_point, pointer) {
                return pointer < (0xa1 - 0x81) * 157 ? null : code_point
            })
        var index_ = big5_index_no_hkscs

        // 2. If code point is U+2550, U+255E, U+2561, U+256A, U+5341, or
        // U+5345, return the last pointer corresponding to code point in
        // index.
        if (
            code_point === 0x2550 ||
            code_point === 0x255e ||
            code_point === 0x2561 ||
            code_point === 0x256a ||
            code_point === 0x5341 ||
            code_point === 0x5345
        ) {
            return index_.lastIndexOf(code_point)
        }

        // 3. Return the index pointer for code point in index.
        return indexPointerFor(code_point, index_)
    }
    var big5_index_no_hkscs

    //
    // 8. API
    //

    /** @const */ var DEFAULT_ENCODING = "utf-8"

    // 8.1 Interface TextDecoder

    /**
     * @constructor
     * @param {string=} label The label of the encoding;
     *     defaults to 'utf-8'.
     * @param {Object=} options
     */
    function TextDecoder(label, options) {
        // Web IDL conventions
        if (!(this instanceof TextDecoder)) throw TypeError("Called as a function. Did you forget 'new'?")
        label = label !== undefined ? String(label) : DEFAULT_ENCODING
        options = ToDictionary(options)

        // A TextDecoder object has an associated encoding, decoder,
        // stream, ignore BOM flag (initially unset), BOM seen flag
        // (initially unset), error mode (initially replacement), and do
        // not flush flag (initially unset).

        /** @private */
        this._encoding = null
        /** @private @type {?Decoder} */
        this._decoder = null
        /** @private @type {boolean} */
        this._ignoreBOM = false
        /** @private @type {boolean} */
        this._BOMseen = false
        /** @private @type {string} */
        this._error_mode = "replacement"
        /** @private @type {boolean} */
        this._do_not_flush = false

        // 1. Let encoding be the result of getting an encoding from
        // label.
        var encoding = getEncoding(label)

        // 2. If encoding is failure or replacement, throw a RangeError.
        if (encoding === null || encoding.name === "replacement") throw RangeError("Unknown encoding: " + label)
        if (!decoders[encoding.name]) {
            throw Error("Decoder not present." + " Did you forget to include encoding-indexes.js first?")
        }

        // 3. Let dec be a new TextDecoder object.
        var dec = this

        // 4. Set dec's encoding to encoding.
        dec._encoding = encoding

        // 5. If options's fatal member is true, set dec's error mode to
        // fatal.
        if (Boolean(options["fatal"])) dec._error_mode = "fatal"

        // 6. If options's ignoreBOM member is true, set dec's ignore BOM
        // flag.
        if (Boolean(options["ignoreBOM"])) dec._ignoreBOM = true

        // For pre-ES5 runtimes:
        if (!Object.defineProperty) {
            this.encoding = dec._encoding.name.toLowerCase()
            this.fatal = dec._error_mode === "fatal"
            this.ignoreBOM = dec._ignoreBOM
        }

        // 7. Return dec.
        return dec
    }

    if (Object.defineProperty) {
        // The encoding attribute's getter must return encoding's name.
        Object.defineProperty(TextDecoder.prototype, "encoding", {
            /** @this {TextDecoder} */
            get: function () {
                return this._encoding.name.toLowerCase()
            },
        })

        // The fatal attribute's getter must return true if error mode
        // is fatal, and false otherwise.
        Object.defineProperty(TextDecoder.prototype, "fatal", {
            /** @this {TextDecoder} */
            get: function () {
                return this._error_mode === "fatal"
            },
        })

        // The ignoreBOM attribute's getter must return true if ignore
        // BOM flag is set, and false otherwise.
        Object.defineProperty(TextDecoder.prototype, "ignoreBOM", {
            /** @this {TextDecoder} */
            get: function () {
                return this._ignoreBOM
            },
        })
    }

    /**
     * @param {BufferSource=} input The buffer of bytes to decode.
     * @param {Object=} options
     * @return {string} The decoded string.
     */
    TextDecoder.prototype.decode = function decode(input, options) {
        var bytes
        if (typeof input === "object" && input instanceof ArrayBuffer) {
            bytes = new Uint8Array(input)
        } else if (typeof input === "object" && "buffer" in input && input.buffer instanceof ArrayBuffer) {
            bytes = new Uint8Array(input.buffer, input.byteOffset, input.byteLength)
        } else {
            bytes = new Uint8Array(0)
        }

        options = ToDictionary(options)

        // 1. If the do not flush flag is unset, set decoder to a new
        // encoding's decoder, set stream to a new stream, and unset the
        // BOM seen flag.
        if (!this._do_not_flush) {
            this._decoder = decoders[this._encoding.name]({
                fatal: this._error_mode === "fatal",
            })
            this._BOMseen = false
        }

        // 2. If options's stream is true, set the do not flush flag, and
        // unset the do not flush flag otherwise.
        this._do_not_flush = Boolean(options["stream"])

        // 3. If input is given, push a copy of input to stream.
        // TODO: Align with spec algorithm - maintain stream on instance.
        var input_stream = new Stream(bytes)

        // 4. Let output be a new stream.
        var output = []

        /** @type {?(number|!Array.<number>)} */
        var result

        // 5. While true:
        while (true) {
            // 1. Let token be the result of reading from stream.
            var token = input_stream.read()

            // 2. If token is end-of-stream and the do not flush flag is
            // set, return output, serialized.
            // TODO: Align with spec algorithm.
            if (token === end_of_stream) break

            // 3. Otherwise, run these subsubsteps:

            // 1. Let result be the result of processing token for decoder,
            // stream, output, and error mode.
            result = this._decoder.handler(input_stream, token)

            // 2. If result is finished, return output, serialized.
            if (result === finished) break

            if (result !== null) {
                if (Array.isArray(result)) output.push.apply(output, /**@type {!Array.<number>}*/ (result))
                else output.push(result)
            }

            // 3. Otherwise, if result is error, throw a TypeError.
            // (Thrown in handler)

            // 4. Otherwise, do nothing.
        }
        // TODO: Align with spec algorithm.
        if (!this._do_not_flush) {
            do {
                result = this._decoder.handler(input_stream, input_stream.read())
                if (result === finished) break
                if (result === null) continue
                if (Array.isArray(result)) output.push.apply(output, /**@type {!Array.<number>}*/ (result))
                else output.push(result)
            } while (!input_stream.endOfStream())
            this._decoder = null
        }

        // A TextDecoder object also has an associated serialize stream
        // algorithm...
        /**
         * @param {!Array.<number>} stream
         * @return {string}
         * @this {TextDecoder}
         */
        function serializeStream(stream) {
            // 1. Let token be the result of reading from stream.
            // (Done in-place on array, rather than as a stream)

            // 2. If encoding is UTF-8, UTF-16BE, or UTF-16LE, and ignore
            // BOM flag and BOM seen flag are unset, run these subsubsteps:
            if (
                includes(["UTF-8", "UTF-16LE", "UTF-16BE"], this._encoding.name) &&
                !this._ignoreBOM &&
                !this._BOMseen
            ) {
                if (stream.length > 0 && stream[0] === 0xfeff) {
                    // 1. If token is U+FEFF, set BOM seen flag.
                    this._BOMseen = true
                    stream.shift()
                } else if (stream.length > 0) {
                    // 2. Otherwise, if token is not end-of-stream, set BOM seen
                    // flag and append token to stream.
                    this._BOMseen = true
                } else {
                    // 3. Otherwise, if token is not end-of-stream, append token
                    // to output.
                    // (no-op)
                }
            }
            // 4. Otherwise, return output.
            return codePointsToString(stream)
        }

        return serializeStream.call(this, output)
    }

    // 8.2 Interface TextEncoder

    /**
     * @constructor
     * @param {string=} label The label of the encoding. NONSTANDARD.
     * @param {Object=} options NONSTANDARD.
     */
    function TextEncoder(label, options) {
        // Web IDL conventions
        if (!(this instanceof TextEncoder)) throw TypeError("Called as a function. Did you forget 'new'?")
        options = ToDictionary(options)

        // A TextEncoder object has an associated encoding and encoder.

        /** @private */
        this._encoding = null
        /** @private @type {?Encoder} */
        this._encoder = null

        // Non-standard
        /** @private @type {boolean} */
        this._do_not_flush = false
        /** @private @type {string} */
        this._fatal = Boolean(options["fatal"]) ? "fatal" : "replacement"

        // 1. Let enc be a new TextEncoder object.
        var enc = this

        // 2. Set enc's encoding to UTF-8's encoder.
        if (Boolean(options["NONSTANDARD_allowLegacyEncoding"])) {
            // NONSTANDARD behavior.
            label = label !== undefined ? String(label) : DEFAULT_ENCODING
            var encoding = getEncoding(label)
            if (encoding === null || encoding.name === "replacement") throw RangeError("Unknown encoding: " + label)
            if (!encoders[encoding.name]) {
                throw Error("Encoder not present." + " Did you forget to include encoding-indexes.js first?")
            }
            enc._encoding = encoding
        } else {
            // Standard behavior.
            enc._encoding = getEncoding("utf-8")

            if (label !== undefined && "console" in global) {
                console.warn("TextEncoder constructor called with encoding label, " + "which is ignored.")
            }
        }

        // For pre-ES5 runtimes:
        if (!Object.defineProperty) this.encoding = enc._encoding.name.toLowerCase()

        // 3. Return enc.
        return enc
    }

    if (Object.defineProperty) {
        // The encoding attribute's getter must return encoding's name.
        Object.defineProperty(TextEncoder.prototype, "encoding", {
            /** @this {TextEncoder} */
            get: function () {
                return this._encoding.name.toLowerCase()
            },
        })
    }

    /**
     * @param {string=} opt_string The string to encode.
     * @param {Object=} options
     * @return {!Uint8Array} Encoded bytes, as a Uint8Array.
     */
    TextEncoder.prototype.encode = function encode(opt_string, options) {
        opt_string = opt_string === undefined ? "" : String(opt_string)
        options = ToDictionary(options)

        // NOTE: This option is nonstandard. None of the encodings
        // permitted for encoding (i.e. UTF-8, UTF-16) are stateful when
        // the input is a USVString so streaming is not necessary.
        if (!this._do_not_flush)
            this._encoder = encoders[this._encoding.name]({
                fatal: this._fatal === "fatal",
            })
        this._do_not_flush = Boolean(options["stream"])

        // 1. Convert input to a stream.
        var input = new Stream(stringToCodePoints(opt_string))

        // 2. Let output be a new stream
        var output = []

        /** @type {?(number|!Array.<number>)} */
        var result
        // 3. While true, run these substeps:
        while (true) {
            // 1. Let token be the result of reading from input.
            var token = input.read()
            if (token === end_of_stream) break
            // 2. Let result be the result of processing token for encoder,
            // input, output.
            result = this._encoder.handler(input, token)
            if (result === finished) break
            if (Array.isArray(result)) output.push.apply(output, /**@type {!Array.<number>}*/ (result))
            else output.push(result)
        }
        // TODO: Align with spec algorithm.
        if (!this._do_not_flush) {
            while (true) {
                result = this._encoder.handler(input, input.read())
                if (result === finished) break
                if (Array.isArray(result)) output.push.apply(output, /**@type {!Array.<number>}*/ (result))
                else output.push(result)
            }
            this._encoder = null
        }
        // 3. If result is finished, convert output into a byte sequence,
        // and then return a Uint8Array object wrapping an ArrayBuffer
        // containing output.
        return new Uint8Array(output)
    }

    //
    // 9. The encoding
    //

    // 9.1 utf-8

    // 9.1.1 utf-8 decoder
    /**
     * @constructor
     * @implements {Decoder}
     * @param {{fatal: boolean}} options
     */
    function UTF8Decoder(options) {
        var fatal = options.fatal

        // utf-8's decoder's has an associated utf-8 code point, utf-8
        // bytes seen, and utf-8 bytes needed (all initially 0), a utf-8
        // lower boundary (initially 0x80), and a utf-8 upper boundary
        // (initially 0xBF).
        var /** @type {number} */ utf8_code_point = 0,
            /** @type {number} */ utf8_bytes_seen = 0,
            /** @type {number} */ utf8_bytes_needed = 0,
            /** @type {number} */ utf8_lower_boundary = 0x80,
            /** @type {number} */ utf8_upper_boundary = 0xbf

        /**
         * @param {Stream} stream The stream of bytes being decoded.
         * @param {number} bite The next byte read from the stream.
         * @return {?(number|!Array.<number>)} The next code point(s)
         *     decoded, or null if not enough data exists in the input
         *     stream to decode a complete code point.
         */
        this.handler = function (stream, bite) {
            // 1. If byte is end-of-stream and utf-8 bytes needed is not 0,
            // set utf-8 bytes needed to 0 and return error.
            if (bite === end_of_stream && utf8_bytes_needed !== 0) {
                utf8_bytes_needed = 0
                return decoderError(fatal)
            }

            // 2. If byte is end-of-stream, return finished.
            if (bite === end_of_stream) return finished

            // 3. If utf-8 bytes needed is 0, based on byte:
            if (utf8_bytes_needed === 0) {
                // 0x00 to 0x7F
                if (inRange(bite, 0x00, 0x7f)) {
                    // Return a code point whose value is byte.
                    return bite
                }

                // 0xC2 to 0xDF
                else if (inRange(bite, 0xc2, 0xdf)) {
                    // 1. Set utf-8 bytes needed to 1.
                    utf8_bytes_needed = 1

                    // 2. Set UTF-8 code point to byte & 0x1F.
                    utf8_code_point = bite & 0x1f
                }

                // 0xE0 to 0xEF
                else if (inRange(bite, 0xe0, 0xef)) {
                    // 1. If byte is 0xE0, set utf-8 lower boundary to 0xA0.
                    if (bite === 0xe0) utf8_lower_boundary = 0xa0
                    // 2. If byte is 0xED, set utf-8 upper boundary to 0x9F.
                    if (bite === 0xed) utf8_upper_boundary = 0x9f
                    // 3. Set utf-8 bytes needed to 2.
                    utf8_bytes_needed = 2
                    // 4. Set UTF-8 code point to byte & 0xF.
                    utf8_code_point = bite & 0xf
                }

                // 0xF0 to 0xF4
                else if (inRange(bite, 0xf0, 0xf4)) {
                    // 1. If byte is 0xF0, set utf-8 lower boundary to 0x90.
                    if (bite === 0xf0) utf8_lower_boundary = 0x90
                    // 2. If byte is 0xF4, set utf-8 upper boundary to 0x8F.
                    if (bite === 0xf4) utf8_upper_boundary = 0x8f
                    // 3. Set utf-8 bytes needed to 3.
                    utf8_bytes_needed = 3
                    // 4. Set UTF-8 code point to byte & 0x7.
                    utf8_code_point = bite & 0x7
                }

                // Otherwise
                else {
                    // Return error.
                    return decoderError(fatal)
                }

                // Return continue.
                return null
            }

            // 4. If byte is not in the range utf-8 lower boundary to utf-8
            // upper boundary, inclusive, run these substeps:
            if (!inRange(bite, utf8_lower_boundary, utf8_upper_boundary)) {
                // 1. Set utf-8 code point, utf-8 bytes needed, and utf-8
                // bytes seen to 0, set utf-8 lower boundary to 0x80, and set
                // utf-8 upper boundary to 0xBF.
                utf8_code_point = utf8_bytes_needed = utf8_bytes_seen = 0
                utf8_lower_boundary = 0x80
                utf8_upper_boundary = 0xbf

                // 2. Prepend byte to stream.
                stream.prepend(bite)

                // 3. Return error.
                return decoderError(fatal)
            }

            // 5. Set utf-8 lower boundary to 0x80 and utf-8 upper boundary
            // to 0xBF.
            utf8_lower_boundary = 0x80
            utf8_upper_boundary = 0xbf

            // 6. Set UTF-8 code point to (UTF-8 code point << 6) | (byte &
            // 0x3F)
            utf8_code_point = (utf8_code_point << 6) | (bite & 0x3f)

            // 7. Increase utf-8 bytes seen by one.
            utf8_bytes_seen += 1

            // 8. If utf-8 bytes seen is not equal to utf-8 bytes needed,
            // continue.
            if (utf8_bytes_seen !== utf8_bytes_needed) return null

            // 9. Let code point be utf-8 code point.
            var code_point = utf8_code_point

            // 10. Set utf-8 code point, utf-8 bytes needed, and utf-8 bytes
            // seen to 0.
            utf8_code_point = utf8_bytes_needed = utf8_bytes_seen = 0

            // 11. Return a code point whose value is code point.
            return code_point
        }
    }

    // 9.1.2 utf-8 encoder
    /**
     * @constructor
     * @implements {Encoder}
     * @param {{fatal: boolean}} options
     */
    function UTF8Encoder(options) {
        var fatal = options.fatal
        /**
         * @param {Stream} stream Input stream.
         * @param {number} code_point Next code point read from the stream.
         * @return {(number|!Array.<number>)} Byte(s) to emit.
         */
        this.handler = function (stream, code_point) {
            // 1. If code point is end-of-stream, return finished.
            if (code_point === end_of_stream) return finished

            // 2. If code point is an ASCII code point, return a byte whose
            // value is code point.
            if (isASCIICodePoint(code_point)) return code_point

            // 3. Set count and offset based on the range code point is in:
            var count, offset
            // U+0080 to U+07FF, inclusive:
            if (inRange(code_point, 0x0080, 0x07ff)) {
                // 1 and 0xC0
                count = 1
                offset = 0xc0
            }
            // U+0800 to U+FFFF, inclusive:
            else if (inRange(code_point, 0x0800, 0xffff)) {
                // 2 and 0xE0
                count = 2
                offset = 0xe0
            }
            // U+10000 to U+10FFFF, inclusive:
            else if (inRange(code_point, 0x10000, 0x10ffff)) {
                // 3 and 0xF0
                count = 3
                offset = 0xf0
            }

            // 4. Let bytes be a byte sequence whose first byte is (code
            // point >> (6 × count)) + offset.
            var bytes = [(code_point >> (6 * count)) + offset]

            // 5. Run these substeps while count is greater than 0:
            while (count > 0) {
                // 1. Set temp to code point >> (6 × (count − 1)).
                var temp = code_point >> (6 * (count - 1))

                // 2. Append to bytes 0x80 | (temp & 0x3F).
                bytes.push(0x80 | (temp & 0x3f))

                // 3. Decrease count by one.
                count -= 1
            }

            // 6. Return bytes bytes, in order.
            return bytes
        }
    }

    /** @param {{fatal: boolean}} options */
    encoders["UTF-8"] = function (options) {
        return new UTF8Encoder(options)
    }
    /** @param {{fatal: boolean}} options */
    decoders["UTF-8"] = function (options) {
        return new UTF8Decoder(options)
    }

    //
    // 10. Legacy single-byte encodings
    //

    // 10.1 single-byte decoder
    /**
     * @constructor
     * @implements {Decoder}
     * @param {!Array.<number>} index The encoding index.
     * @param {{fatal: boolean}} options
     */
    function SingleByteDecoder(index, options) {
        var fatal = options.fatal
        /**
         * @param {Stream} stream The stream of bytes being decoded.
         * @param {number} bite The next byte read from the stream.
         * @return {?(number|!Array.<number>)} The next code point(s)
         *     decoded, or null if not enough data exists in the input
         *     stream to decode a complete code point.
         */
        this.handler = function (stream, bite) {
            // 1. If byte is end-of-stream, return finished.
            if (bite === end_of_stream) return finished

            // 2. If byte is an ASCII byte, return a code point whose value
            // is byte.
            if (isASCIIByte(bite)) return bite

            // 3. Let code point be the index code point for byte − 0x80 in
            // index single-byte.
            var code_point = index[bite - 0x80]

            // 4. If code point is null, return error.
            if (code_point === null) return decoderError(fatal)

            // 5. Return a code point whose value is code point.
            return code_point
        }
    }

    // 10.2 single-byte encoder
    /**
     * @constructor
     * @implements {Encoder}
     * @param {!Array.<?number>} index The encoding index.
     * @param {{fatal: boolean}} options
     */
    function SingleByteEncoder(index, options) {
        var fatal = options.fatal
        /**
         * @param {Stream} stream Input stream.
         * @param {number} code_point Next code point read from the stream.
         * @return {(number|!Array.<number>)} Byte(s) to emit.
         */
        this.handler = function (stream, code_point) {
            // 1. If code point is end-of-stream, return finished.
            if (code_point === end_of_stream) return finished

            // 2. If code point is an ASCII code point, return a byte whose
            // value is code point.
            if (isASCIICodePoint(code_point)) return code_point

            // 3. Let pointer be the index pointer for code point in index
            // single-byte.
            var pointer = indexPointerFor(code_point, index)

            // 4. If pointer is null, return error with code point.
            if (pointer === null) encoderError(code_point)

            // 5. Return a byte whose value is pointer + 0x80.
            return pointer + 0x80
        }
    }

    ;(function () {
        if (!("encoding-indexes" in global)) return
        encodings.forEach(function (category) {
            if (category.heading !== "Legacy single-byte encodings") return
            category.encodings.forEach(function (encoding) {
                var name = encoding.name
                var idx = index(name.toLowerCase())
                /** @param {{fatal: boolean}} options */
                decoders[name] = function (options) {
                    return new SingleByteDecoder(idx, options)
                }
                /** @param {{fatal: boolean}} options */
                encoders[name] = function (options) {
                    return new SingleByteEncoder(idx, options)
                }
            })
        })
    })()

    //
    // 11. Legacy multi-byte Chinese (simplified) encodings
    //

    // 11.1 gbk

    // 11.1.1 gbk decoder
    // gbk's decoder is gb18030's decoder.
    /** @param {{fatal: boolean}} options */
    decoders["GBK"] = function (options) {
        return new GB18030Decoder(options)
    }

    // 11.1.2 gbk encoder
    // gbk's encoder is gb18030's encoder with its gbk flag set.
    /** @param {{fatal: boolean}} options */
    encoders["GBK"] = function (options) {
        return new GB18030Encoder(options, true)
    }

    // 11.2 gb18030
    // 11.2.1 gb18030 decoder
    /**
     * @constructor
     * @implements {Decoder}
     * @param {{fatal: boolean}} options
     */
    function GB18030Decoder(options) {
        var fatal = options.fatal
        // gb18030's decoder has an associated gb18030 first, gb18030
        // second, and gb18030 third (all initially 0x00).
        var /** @type {number} */ gb18030_first = 0x00,
            /** @type {number} */ gb18030_second = 0x00,
            /** @type {number} */ gb18030_third = 0x00
        /**
         * @param {Stream} stream The stream of bytes being decoded.
         * @param {number} bite The next byte read from the stream.
         * @return {?(number|!Array.<number>)} The next code point(s)
         *     decoded, or null if not enough data exists in the input
         *     stream to decode a complete code point.
         */
        this.handler = function (stream, bite) {
            // 1. If byte is end-of-stream and gb18030 first, gb18030
            // second, and gb18030 third are 0x00, return finished.
            if (bite === end_of_stream && gb18030_first === 0x00 && gb18030_second === 0x00 && gb18030_third === 0x00) {
                return finished
            }
            // 2. If byte is end-of-stream, and gb18030 first, gb18030
            // second, or gb18030 third is not 0x00, set gb18030 first,
            // gb18030 second, and gb18030 third to 0x00, and return error.
            if (
                bite === end_of_stream &&
                (gb18030_first !== 0x00 || gb18030_second !== 0x00 || gb18030_third !== 0x00)
            ) {
                gb18030_first = 0x00
                gb18030_second = 0x00
                gb18030_third = 0x00
                decoderError(fatal)
            }
            var code_point
            // 3. If gb18030 third is not 0x00, run these substeps:
            if (gb18030_third !== 0x00) {
                // 1. Let code point be null.
                code_point = null
                // 2. If byte is in the range 0x30 to 0x39, inclusive, set
                // code point to the index gb18030 ranges code point for
                // (((gb18030 first − 0x81) × 10 + gb18030 second − 0x30) ×
                // 126 + gb18030 third − 0x81) × 10 + byte − 0x30.
                if (inRange(bite, 0x30, 0x39)) {
                    code_point = indexGB18030RangesCodePointFor(
                        (((gb18030_first - 0x81) * 10 + gb18030_second - 0x30) * 126 + gb18030_third - 0x81) * 10 +
                            bite -
                            0x30,
                    )
                }

                // 3. Let buffer be a byte sequence consisting of gb18030
                // second, gb18030 third, and byte, in order.
                var buffer = [gb18030_second, gb18030_third, bite]

                // 4. Set gb18030 first, gb18030 second, and gb18030 third to
                // 0x00.
                gb18030_first = 0x00
                gb18030_second = 0x00
                gb18030_third = 0x00

                // 5. If code point is null, prepend buffer to stream and
                // return error.
                if (code_point === null) {
                    stream.prepend(buffer)
                    return decoderError(fatal)
                }

                // 6. Return a code point whose value is code point.
                return code_point
            }

            // 4. If gb18030 second is not 0x00, run these substeps:
            if (gb18030_second !== 0x00) {
                // 1. If byte is in the range 0x81 to 0xFE, inclusive, set
                // gb18030 third to byte and return continue.
                if (inRange(bite, 0x81, 0xfe)) {
                    gb18030_third = bite
                    return null
                }

                // 2. Prepend gb18030 second followed by byte to stream, set
                // gb18030 first and gb18030 second to 0x00, and return error.
                stream.prepend([gb18030_second, bite])
                gb18030_first = 0x00
                gb18030_second = 0x00
                return decoderError(fatal)
            }

            // 5. If gb18030 first is not 0x00, run these substeps:
            if (gb18030_first !== 0x00) {
                // 1. If byte is in the range 0x30 to 0x39, inclusive, set
                // gb18030 second to byte and return continue.
                if (inRange(bite, 0x30, 0x39)) {
                    gb18030_second = bite
                    return null
                }

                // 2. Let lead be gb18030 first, let pointer be null, and set
                // gb18030 first to 0x00.
                var lead = gb18030_first
                var pointer = null
                gb18030_first = 0x00

                // 3. Let offset be 0x40 if byte is less than 0x7F and 0x41
                // otherwise.
                var offset = bite < 0x7f ? 0x40 : 0x41

                // 4. If byte is in the range 0x40 to 0x7E, inclusive, or 0x80
                // to 0xFE, inclusive, set pointer to (lead − 0x81) × 190 +
                // (byte − offset).
                if (inRange(bite, 0x40, 0x7e) || inRange(bite, 0x80, 0xfe))
                    pointer = (lead - 0x81) * 190 + (bite - offset)

                // 5. Let code point be null if pointer is null and the index
                // code point for pointer in index gb18030 otherwise.
                code_point = pointer === null ? null : indexCodePointFor(pointer, index("gb18030"))

                // 6. If code point is null and byte is an ASCII byte, prepend
                // byte to stream.
                if (code_point === null && isASCIIByte(bite)) stream.prepend(bite)

                // 7. If code point is null, return error.
                if (code_point === null) return decoderError(fatal)

                // 8. Return a code point whose value is code point.
                return code_point
            }

            // 6. If byte is an ASCII byte, return a code point whose value
            // is byte.
            if (isASCIIByte(bite)) return bite

            // 7. If byte is 0x80, return code point U+20AC.
            if (bite === 0x80) return 0x20ac

            // 8. If byte is in the range 0x81 to 0xFE, inclusive, set
            // gb18030 first to byte and return continue.
            if (inRange(bite, 0x81, 0xfe)) {
                gb18030_first = bite
                return null
            }

            // 9. Return error.
            return decoderError(fatal)
        }
    }

    // 11.2.2 gb18030 encoder
    /**
     * @constructor
     * @implements {Encoder}
     * @param {{fatal: boolean}} options
     * @param {boolean=} gbk_flag
     */
    function GB18030Encoder(options, gbk_flag) {
        var fatal = options.fatal
        // gb18030's decoder has an associated gbk flag (initially unset).
        /**
         * @param {Stream} stream Input stream.
         * @param {number} code_point Next code point read from the stream.
         * @return {(number|!Array.<number>)} Byte(s) to emit.
         */
        this.handler = function (stream, code_point) {
            // 1. If code point is end-of-stream, return finished.
            if (code_point === end_of_stream) return finished

            // 2. If code point is an ASCII code point, return a byte whose
            // value is code point.
            if (isASCIICodePoint(code_point)) return code_point

            // 3. If code point is U+E5E5, return error with code point.
            if (code_point === 0xe5e5) return encoderError(code_point)

            // 4. If the gbk flag is set and code point is U+20AC, return
            // byte 0x80.
            if (gbk_flag && code_point === 0x20ac) return 0x80

            // 5. Let pointer be the index pointer for code point in index
            // gb18030.
            var pointer = indexPointerFor(code_point, index("gb18030"))

            // 6. If pointer is not null, run these substeps:
            if (pointer !== null) {
                // 1. Let lead be floor(pointer / 190) + 0x81.
                var lead = floor(pointer / 190) + 0x81

                // 2. Let trail be pointer % 190.
                var trail = pointer % 190

                // 3. Let offset be 0x40 if trail is less than 0x3F and 0x41 otherwise.
                var offset = trail < 0x3f ? 0x40 : 0x41

                // 4. Return two bytes whose values are lead and trail + offset.
                return [lead, trail + offset]
            }

            // 7. If gbk flag is set, return error with code point.
            if (gbk_flag) return encoderError(code_point)

            // 8. Set pointer to the index gb18030 ranges pointer for code
            // point.
            pointer = indexGB18030RangesPointerFor(code_point)

            // 9. Let byte1 be floor(pointer / 10 / 126 / 10).
            var byte1 = floor(pointer / 10 / 126 / 10)

            // 10. Set pointer to pointer − byte1 × 10 × 126 × 10.
            pointer = pointer - byte1 * 10 * 126 * 10

            // 11. Let byte2 be floor(pointer / 10 / 126).
            var byte2 = floor(pointer / 10 / 126)

            // 12. Set pointer to pointer − byte2 × 10 × 126.
            pointer = pointer - byte2 * 10 * 126

            // 13. Let byte3 be floor(pointer / 10).
            var byte3 = floor(pointer / 10)

            // 14. Let byte4 be pointer − byte3 × 10.
            var byte4 = pointer - byte3 * 10

            // 15. Return four bytes whose values are byte1 + 0x81, byte2 +
            // 0x30, byte3 + 0x81, byte4 + 0x30.
            return [byte1 + 0x81, byte2 + 0x30, byte3 + 0x81, byte4 + 0x30]
        }
    }

    /** @param {{fatal: boolean}} options */
    encoders["gb18030"] = function (options) {
        return new GB18030Encoder(options)
    }
    /** @param {{fatal: boolean}} options */
    decoders["gb18030"] = function (options) {
        return new GB18030Decoder(options)
    }

    //
    // 12. Legacy multi-byte Chinese (traditional) encodings
    //

    // 12.1 Big5

    // 12.1.1 Big5 decoder
    /**
     * @constructor
     * @implements {Decoder}
     * @param {{fatal: boolean}} options
     */
    function Big5Decoder(options) {
        var fatal = options.fatal
        // Big5's decoder has an associated Big5 lead (initially 0x00).
        var /** @type {number} */ Big5_lead = 0x00

        /**
         * @param {Stream} stream The stream of bytes being decoded.
         * @param {number} bite The next byte read from the stream.
         * @return {?(number|!Array.<number>)} The next code point(s)
         *     decoded, or null if not enough data exists in the input
         *     stream to decode a complete code point.
         */
        this.handler = function (stream, bite) {
            // 1. If byte is end-of-stream and Big5 lead is not 0x00, set
            // Big5 lead to 0x00 and return error.
            if (bite === end_of_stream && Big5_lead !== 0x00) {
                Big5_lead = 0x00
                return decoderError(fatal)
            }

            // 2. If byte is end-of-stream and Big5 lead is 0x00, return
            // finished.
            if (bite === end_of_stream && Big5_lead === 0x00) return finished

            // 3. If Big5 lead is not 0x00, let lead be Big5 lead, let
            // pointer be null, set Big5 lead to 0x00, and then run these
            // substeps:
            if (Big5_lead !== 0x00) {
                var lead = Big5_lead
                var pointer = null
                Big5_lead = 0x00

                // 1. Let offset be 0x40 if byte is less than 0x7F and 0x62
                // otherwise.
                var offset = bite < 0x7f ? 0x40 : 0x62

                // 2. If byte is in the range 0x40 to 0x7E, inclusive, or 0xA1
                // to 0xFE, inclusive, set pointer to (lead − 0x81) × 157 +
                // (byte − offset).
                if (inRange(bite, 0x40, 0x7e) || inRange(bite, 0xa1, 0xfe))
                    pointer = (lead - 0x81) * 157 + (bite - offset)

                // 3. If there is a row in the table below whose first column
                // is pointer, return the two code points listed in its second
                // column
                // Pointer | Code points
                // --------+--------------
                // 1133    | U+00CA U+0304
                // 1135    | U+00CA U+030C
                // 1164    | U+00EA U+0304
                // 1166    | U+00EA U+030C
                switch (pointer) {
                    case 1133:
                        return [0x00ca, 0x0304]
                    case 1135:
                        return [0x00ca, 0x030c]
                    case 1164:
                        return [0x00ea, 0x0304]
                    case 1166:
                        return [0x00ea, 0x030c]
                }

                // 4. Let code point be null if pointer is null and the index
                // code point for pointer in index Big5 otherwise.
                var code_point = pointer === null ? null : indexCodePointFor(pointer, index("big5"))

                // 5. If code point is null and byte is an ASCII byte, prepend
                // byte to stream.
                if (code_point === null && isASCIIByte(bite)) stream.prepend(bite)

                // 6. If code point is null, return error.
                if (code_point === null) return decoderError(fatal)

                // 7. Return a code point whose value is code point.
                return code_point
            }

            // 4. If byte is an ASCII byte, return a code point whose value
            // is byte.
            if (isASCIIByte(bite)) return bite

            // 5. If byte is in the range 0x81 to 0xFE, inclusive, set Big5
            // lead to byte and return continue.
            if (inRange(bite, 0x81, 0xfe)) {
                Big5_lead = bite
                return null
            }

            // 6. Return error.
            return decoderError(fatal)
        }
    }

    // 12.1.2 Big5 encoder
    /**
     * @constructor
     * @implements {Encoder}
     * @param {{fatal: boolean}} options
     */
    function Big5Encoder(options) {
        var fatal = options.fatal
        /**
         * @param {Stream} stream Input stream.
         * @param {number} code_point Next code point read from the stream.
         * @return {(number|!Array.<number>)} Byte(s) to emit.
         */
        this.handler = function (stream, code_point) {
            // 1. If code point is end-of-stream, return finished.
            if (code_point === end_of_stream) return finished

            // 2. If code point is an ASCII code point, return a byte whose
            // value is code point.
            if (isASCIICodePoint(code_point)) return code_point

            // 3. Let pointer be the index Big5 pointer for code point.
            var pointer = indexBig5PointerFor(code_point)

            // 4. If pointer is null, return error with code point.
            if (pointer === null) return encoderError(code_point)

            // 5. Let lead be floor(pointer / 157) + 0x81.
            var lead = floor(pointer / 157) + 0x81

            // 6. If lead is less than 0xA1, return error with code point.
            if (lead < 0xa1) return encoderError(code_point)

            // 7. Let trail be pointer % 157.
            var trail = pointer % 157

            // 8. Let offset be 0x40 if trail is less than 0x3F and 0x62
            // otherwise.
            var offset = trail < 0x3f ? 0x40 : 0x62

            // Return two bytes whose values are lead and trail + offset.
            return [lead, trail + offset]
        }
    }

    /** @param {{fatal: boolean}} options */
    encoders["Big5"] = function (options) {
        return new Big5Encoder(options)
    }
    /** @param {{fatal: boolean}} options */
    decoders["Big5"] = function (options) {
        return new Big5Decoder(options)
    }

    //
    // 13. Legacy multi-byte Japanese encodings
    //

    // 13.1 euc-jp

    // 13.1.1 euc-jp decoder
    /**
     * @constructor
     * @implements {Decoder}
     * @param {{fatal: boolean}} options
     */
    function EUCJPDecoder(options) {
        var fatal = options.fatal

        // euc-jp's decoder has an associated euc-jp jis0212 flag
        // (initially unset) and euc-jp lead (initially 0x00).
        var /** @type {boolean} */ eucjp_jis0212_flag = false,
            /** @type {number} */ eucjp_lead = 0x00

        /**
         * @param {Stream} stream The stream of bytes being decoded.
         * @param {number} bite The next byte read from the stream.
         * @return {?(number|!Array.<number>)} The next code point(s)
         *     decoded, or null if not enough data exists in the input
         *     stream to decode a complete code point.
         */
        this.handler = function (stream, bite) {
            // 1. If byte is end-of-stream and euc-jp lead is not 0x00, set
            // euc-jp lead to 0x00, and return error.
            if (bite === end_of_stream && eucjp_lead !== 0x00) {
                eucjp_lead = 0x00
                return decoderError(fatal)
            }

            // 2. If byte is end-of-stream and euc-jp lead is 0x00, return
            // finished.
            if (bite === end_of_stream && eucjp_lead === 0x00) return finished

            // 3. If euc-jp lead is 0x8E and byte is in the range 0xA1 to
            // 0xDF, inclusive, set euc-jp lead to 0x00 and return a code
            // point whose value is 0xFF61 − 0xA1 + byte.
            if (eucjp_lead === 0x8e && inRange(bite, 0xa1, 0xdf)) {
                eucjp_lead = 0x00
                return 0xff61 - 0xa1 + bite
            }

            // 4. If euc-jp lead is 0x8F and byte is in the range 0xA1 to
            // 0xFE, inclusive, set the euc-jp jis0212 flag, set euc-jp lead
            // to byte, and return continue.
            if (eucjp_lead === 0x8f && inRange(bite, 0xa1, 0xfe)) {
                eucjp_jis0212_flag = true
                eucjp_lead = bite
                return null
            }

            // 5. If euc-jp lead is not 0x00, let lead be euc-jp lead, set
            // euc-jp lead to 0x00, and run these substeps:
            if (eucjp_lead !== 0x00) {
                var lead = eucjp_lead
                eucjp_lead = 0x00

                // 1. Let code point be null.
                var code_point = null

                // 2. If lead and byte are both in the range 0xA1 to 0xFE,
                // inclusive, set code point to the index code point for (lead
                // − 0xA1) × 94 + byte − 0xA1 in index jis0208 if the euc-jp
                // jis0212 flag is unset and in index jis0212 otherwise.
                if (inRange(lead, 0xa1, 0xfe) && inRange(bite, 0xa1, 0xfe)) {
                    code_point = indexCodePointFor(
                        (lead - 0xa1) * 94 + (bite - 0xa1),
                        index(!eucjp_jis0212_flag ? "jis0208" : "jis0212"),
                    )
                }

                // 3. Unset the euc-jp jis0212 flag.
                eucjp_jis0212_flag = false

                // 4. If byte is not in the range 0xA1 to 0xFE, inclusive,
                // prepend byte to stream.
                if (!inRange(bite, 0xa1, 0xfe)) stream.prepend(bite)

                // 5. If code point is null, return error.
                if (code_point === null) return decoderError(fatal)

                // 6. Return a code point whose value is code point.
                return code_point
            }

            // 6. If byte is an ASCII byte, return a code point whose value
            // is byte.
            if (isASCIIByte(bite)) return bite

            // 7. If byte is 0x8E, 0x8F, or in the range 0xA1 to 0xFE,
            // inclusive, set euc-jp lead to byte and return continue.
            if (bite === 0x8e || bite === 0x8f || inRange(bite, 0xa1, 0xfe)) {
                eucjp_lead = bite
                return null
            }

            // 8. Return error.
            return decoderError(fatal)
        }
    }

    // 13.1.2 euc-jp encoder
    /**
     * @constructor
     * @implements {Encoder}
     * @param {{fatal: boolean}} options
     */
    function EUCJPEncoder(options) {
        var fatal = options.fatal
        /**
         * @param {Stream} stream Input stream.
         * @param {number} code_point Next code point read from the stream.
         * @return {(number|!Array.<number>)} Byte(s) to emit.
         */
        this.handler = function (stream, code_point) {
            // 1. If code point is end-of-stream, return finished.
            if (code_point === end_of_stream) return finished

            // 2. If code point is an ASCII code point, return a byte whose
            // value is code point.
            if (isASCIICodePoint(code_point)) return code_point

            // 3. If code point is U+00A5, return byte 0x5C.
            if (code_point === 0x00a5) return 0x5c

            // 4. If code point is U+203E, return byte 0x7E.
            if (code_point === 0x203e) return 0x7e

            // 5. If code point is in the range U+FF61 to U+FF9F, inclusive,
            // return two bytes whose values are 0x8E and code point −
            // 0xFF61 + 0xA1.
            if (inRange(code_point, 0xff61, 0xff9f)) return [0x8e, code_point - 0xff61 + 0xa1]

            // 6. If code point is U+2212, set it to U+FF0D.
            if (code_point === 0x2212) code_point = 0xff0d

            // 7. Let pointer be the index pointer for code point in index
            // jis0208.
            var pointer = indexPointerFor(code_point, index("jis0208"))

            // 8. If pointer is null, return error with code point.
            if (pointer === null) return encoderError(code_point)

            // 9. Let lead be floor(pointer / 94) + 0xA1.
            var lead = floor(pointer / 94) + 0xa1

            // 10. Let trail be pointer % 94 + 0xA1.
            var trail = (pointer % 94) + 0xa1

            // 11. Return two bytes whose values are lead and trail.
            return [lead, trail]
        }
    }

    /** @param {{fatal: boolean}} options */
    encoders["EUC-JP"] = function (options) {
        return new EUCJPEncoder(options)
    }
    /** @param {{fatal: boolean}} options */
    decoders["EUC-JP"] = function (options) {
        return new EUCJPDecoder(options)
    }

    // 13.2 iso-2022-jp

    // 13.2.1 iso-2022-jp decoder
    /**
     * @constructor
     * @implements {Decoder}
     * @param {{fatal: boolean}} options
     */
    function ISO2022JPDecoder(options) {
        var fatal = options.fatal
        /** @enum */
        var states = {
            ASCII: 0,
            Roman: 1,
            Katakana: 2,
            LeadByte: 3,
            TrailByte: 4,
            EscapeStart: 5,
            Escape: 6,
        }
        // iso-2022-jp's decoder has an associated iso-2022-jp decoder
        // state (initially ASCII), iso-2022-jp decoder output state
        // (initially ASCII), iso-2022-jp lead (initially 0x00), and
        // iso-2022-jp output flag (initially unset).
        var /** @type {number} */ iso2022jp_decoder_state = states.ASCII,
            /** @type {number} */ iso2022jp_decoder_output_state = states.ASCII,
            /** @type {number} */ iso2022jp_lead = 0x00,
            /** @type {boolean} */ iso2022jp_output_flag = false
        /**
         * @param {Stream} stream The stream of bytes being decoded.
         * @param {number} bite The next byte read from the stream.
         * @return {?(number|!Array.<number>)} The next code point(s)
         *     decoded, or null if not enough data exists in the input
         *     stream to decode a complete code point.
         */
        this.handler = function (stream, bite) {
            // switching on iso-2022-jp decoder state:
            switch (iso2022jp_decoder_state) {
                default:
                case states.ASCII:
                    // ASCII
                    // Based on byte:

                    // 0x1B
                    if (bite === 0x1b) {
                        // Set iso-2022-jp decoder state to escape start and return
                        // continue.
                        iso2022jp_decoder_state = states.EscapeStart
                        return null
                    }

                    // 0x00 to 0x7F, excluding 0x0E, 0x0F, and 0x1B
                    if (inRange(bite, 0x00, 0x7f) && bite !== 0x0e && bite !== 0x0f && bite !== 0x1b) {
                        // Unset the iso-2022-jp output flag and return a code point
                        // whose value is byte.
                        iso2022jp_output_flag = false
                        return bite
                    }

                    // end-of-stream
                    if (bite === end_of_stream) {
                        // Return finished.
                        return finished
                    }

                    // Otherwise
                    // Unset the iso-2022-jp output flag and return error.
                    iso2022jp_output_flag = false
                    return decoderError(fatal)

                case states.Roman:
                    // Roman
                    // Based on byte:

                    // 0x1B
                    if (bite === 0x1b) {
                        // Set iso-2022-jp decoder state to escape start and return
                        // continue.
                        iso2022jp_decoder_state = states.EscapeStart
                        return null
                    }

                    // 0x5C
                    if (bite === 0x5c) {
                        // Unset the iso-2022-jp output flag and return code point
                        // U+00A5.
                        iso2022jp_output_flag = false
                        return 0x00a5
                    }

                    // 0x7E
                    if (bite === 0x7e) {
                        // Unset the iso-2022-jp output flag and return code point
                        // U+203E.
                        iso2022jp_output_flag = false
                        return 0x203e
                    }

                    // 0x00 to 0x7F, excluding 0x0E, 0x0F, 0x1B, 0x5C, and 0x7E
                    if (
                        inRange(bite, 0x00, 0x7f) &&
                        bite !== 0x0e &&
                        bite !== 0x0f &&
                        bite !== 0x1b &&
                        bite !== 0x5c &&
                        bite !== 0x7e
                    ) {
                        // Unset the iso-2022-jp output flag and return a code point
                        // whose value is byte.
                        iso2022jp_output_flag = false
                        return bite
                    }

                    // end-of-stream
                    if (bite === end_of_stream) {
                        // Return finished.
                        return finished
                    }

                    // Otherwise
                    // Unset the iso-2022-jp output flag and return error.
                    iso2022jp_output_flag = false
                    return decoderError(fatal)

                case states.Katakana:
                    // Katakana
                    // Based on byte:

                    // 0x1B
                    if (bite === 0x1b) {
                        // Set iso-2022-jp decoder state to escape start and return
                        // continue.
                        iso2022jp_decoder_state = states.EscapeStart
                        return null
                    }

                    // 0x21 to 0x5F
                    if (inRange(bite, 0x21, 0x5f)) {
                        // Unset the iso-2022-jp output flag and return a code point
                        // whose value is 0xFF61 − 0x21 + byte.
                        iso2022jp_output_flag = false
                        return 0xff61 - 0x21 + bite
                    }

                    // end-of-stream
                    if (bite === end_of_stream) {
                        // Return finished.
                        return finished
                    }

                    // Otherwise
                    // Unset the iso-2022-jp output flag and return error.
                    iso2022jp_output_flag = false
                    return decoderError(fatal)

                case states.LeadByte:
                    // Lead byte
                    // Based on byte:

                    // 0x1B
                    if (bite === 0x1b) {
                        // Set iso-2022-jp decoder state to escape start and return
                        // continue.
                        iso2022jp_decoder_state = states.EscapeStart
                        return null
                    }

                    // 0x21 to 0x7E
                    if (inRange(bite, 0x21, 0x7e)) {
                        // Unset the iso-2022-jp output flag, set iso-2022-jp lead
                        // to byte, iso-2022-jp decoder state to trail byte, and
                        // return continue.
                        iso2022jp_output_flag = false
                        iso2022jp_lead = bite
                        iso2022jp_decoder_state = states.TrailByte
                        return null
                    }

                    // end-of-stream
                    if (bite === end_of_stream) {
                        // Return finished.
                        return finished
                    }

                    // Otherwise
                    // Unset the iso-2022-jp output flag and return error.
                    iso2022jp_output_flag = false
                    return decoderError(fatal)

                case states.TrailByte:
                    // Trail byte
                    // Based on byte:

                    // 0x1B
                    if (bite === 0x1b) {
                        // Set iso-2022-jp decoder state to escape start and return
                        // continue.
                        iso2022jp_decoder_state = states.EscapeStart
                        return decoderError(fatal)
                    }

                    // 0x21 to 0x7E
                    if (inRange(bite, 0x21, 0x7e)) {
                        // 1. Set the iso-2022-jp decoder state to lead byte.
                        iso2022jp_decoder_state = states.LeadByte

                        // 2. Let pointer be (iso-2022-jp lead − 0x21) × 94 + byte − 0x21.
                        var pointer = (iso2022jp_lead - 0x21) * 94 + bite - 0x21

                        // 3. Let code point be the index code point for pointer in
                        // index jis0208.
                        var code_point = indexCodePointFor(pointer, index("jis0208"))

                        // 4. If code point is null, return error.
                        if (code_point === null) return decoderError(fatal)

                        // 5. Return a code point whose value is code point.
                        return code_point
                    }

                    // end-of-stream
                    if (bite === end_of_stream) {
                        // Set the iso-2022-jp decoder state to lead byte, prepend
                        // byte to stream, and return error.
                        iso2022jp_decoder_state = states.LeadByte
                        stream.prepend(bite)
                        return decoderError(fatal)
                    }

                    // Otherwise
                    // Set iso-2022-jp decoder state to lead byte and return
                    // error.
                    iso2022jp_decoder_state = states.LeadByte
                    return decoderError(fatal)

                case states.EscapeStart:
                    // Escape start

                    // 1. If byte is either 0x24 or 0x28, set iso-2022-jp lead to
                    // byte, iso-2022-jp decoder state to escape, and return
                    // continue.
                    if (bite === 0x24 || bite === 0x28) {
                        iso2022jp_lead = bite
                        iso2022jp_decoder_state = states.Escape
                        return null
                    }

                    // 2. Prepend byte to stream.
                    stream.prepend(bite)

                    // 3. Unset the iso-2022-jp output flag, set iso-2022-jp
                    // decoder state to iso-2022-jp decoder output state, and
                    // return error.
                    iso2022jp_output_flag = false
                    iso2022jp_decoder_state = iso2022jp_decoder_output_state
                    return decoderError(fatal)

                case states.Escape:
                    // Escape

                    // 1. Let lead be iso-2022-jp lead and set iso-2022-jp lead to
                    // 0x00.
                    var lead = iso2022jp_lead
                    iso2022jp_lead = 0x00

                    // 2. Let state be null.
                    var state = null

                    // 3. If lead is 0x28 and byte is 0x42, set state to ASCII.
                    if (lead === 0x28 && bite === 0x42) state = states.ASCII

                    // 4. If lead is 0x28 and byte is 0x4A, set state to Roman.
                    if (lead === 0x28 && bite === 0x4a) state = states.Roman

                    // 5. If lead is 0x28 and byte is 0x49, set state to Katakana.
                    if (lead === 0x28 && bite === 0x49) state = states.Katakana

                    // 6. If lead is 0x24 and byte is either 0x40 or 0x42, set
                    // state to lead byte.
                    if (lead === 0x24 && (bite === 0x40 || bite === 0x42)) state = states.LeadByte

                    // 7. If state is non-null, run these substeps:
                    if (state !== null) {
                        // 1. Set iso-2022-jp decoder state and iso-2022-jp decoder
                        // output state to states.
                        iso2022jp_decoder_state = iso2022jp_decoder_state = state

                        // 2. Let output flag be the iso-2022-jp output flag.
                        var output_flag = iso2022jp_output_flag

                        // 3. Set the iso-2022-jp output flag.
                        iso2022jp_output_flag = true

                        // 4. Return continue, if output flag is unset, and error
                        // otherwise.
                        return !output_flag ? null : decoderError(fatal)
                    }

                    // 8. Prepend lead and byte to stream.
                    stream.prepend([lead, bite])

                    // 9. Unset the iso-2022-jp output flag, set iso-2022-jp
                    // decoder state to iso-2022-jp decoder output state and
                    // return error.
                    iso2022jp_output_flag = false
                    iso2022jp_decoder_state = iso2022jp_decoder_output_state
                    return decoderError(fatal)
            }
        }
    }

    // 13.2.2 iso-2022-jp encoder
    /**
     * @constructor
     * @implements {Encoder}
     * @param {{fatal: boolean}} options
     */
    function ISO2022JPEncoder(options) {
        var fatal = options.fatal
        // iso-2022-jp's encoder has an associated iso-2022-jp encoder
        // state which is one of ASCII, Roman, and jis0208 (initially
        // ASCII).
        /** @enum */
        var states = {
            ASCII: 0,
            Roman: 1,
            jis0208: 2,
        }
        var /** @type {number} */ iso2022jp_state = states.ASCII
        /**
         * @param {Stream} stream Input stream.
         * @param {number} code_point Next code point read from the stream.
         * @return {(number|!Array.<number>)} Byte(s) to emit.
         */
        this.handler = function (stream, code_point) {
            // 1. If code point is end-of-stream and iso-2022-jp encoder
            // state is not ASCII, prepend code point to stream, set
            // iso-2022-jp encoder state to ASCII, and return three bytes
            // 0x1B 0x28 0x42.
            if (code_point === end_of_stream && iso2022jp_state !== states.ASCII) {
                stream.prepend(code_point)
                iso2022jp_state = states.ASCII
                return [0x1b, 0x28, 0x42]
            }

            // 2. If code point is end-of-stream and iso-2022-jp encoder
            // state is ASCII, return finished.
            if (code_point === end_of_stream && iso2022jp_state === states.ASCII) return finished

            // 3. If ISO-2022-JP encoder state is ASCII or Roman, and code
            // point is U+000E, U+000F, or U+001B, return error with U+FFFD.
            if (
                (iso2022jp_state === states.ASCII || iso2022jp_state === states.Roman) &&
                (code_point === 0x000e || code_point === 0x000f || code_point === 0x001b)
            ) {
                return encoderError(0xfffd)
            }

            // 4. If iso-2022-jp encoder state is ASCII and code point is an
            // ASCII code point, return a byte whose value is code point.
            if (iso2022jp_state === states.ASCII && isASCIICodePoint(code_point)) return code_point

            // 5. If iso-2022-jp encoder state is Roman and code point is an
            // ASCII code point, excluding U+005C and U+007E, or is U+00A5
            // or U+203E, run these substeps:
            if (
                iso2022jp_state === states.Roman &&
                ((isASCIICodePoint(code_point) && code_point !== 0x005c && code_point !== 0x007e) ||
                    code_point == 0x00a5 ||
                    code_point == 0x203e)
            ) {
                // 1. If code point is an ASCII code point, return a byte
                // whose value is code point.
                if (isASCIICodePoint(code_point)) return code_point

                // 2. If code point is U+00A5, return byte 0x5C.
                if (code_point === 0x00a5) return 0x5c

                // 3. If code point is U+203E, return byte 0x7E.
                if (code_point === 0x203e) return 0x7e
            }

            // 6. If code point is an ASCII code point, and iso-2022-jp
            // encoder state is not ASCII, prepend code point to stream, set
            // iso-2022-jp encoder state to ASCII, and return three bytes
            // 0x1B 0x28 0x42.
            if (isASCIICodePoint(code_point) && iso2022jp_state !== states.ASCII) {
                stream.prepend(code_point)
                iso2022jp_state = states.ASCII
                return [0x1b, 0x28, 0x42]
            }

            // 7. If code point is either U+00A5 or U+203E, and iso-2022-jp
            // encoder state is not Roman, prepend code point to stream, set
            // iso-2022-jp encoder state to Roman, and return three bytes
            // 0x1B 0x28 0x4A.
            if ((code_point === 0x00a5 || code_point === 0x203e) && iso2022jp_state !== states.Roman) {
                stream.prepend(code_point)
                iso2022jp_state = states.Roman
                return [0x1b, 0x28, 0x4a]
            }

            // 8. If code point is U+2212, set it to U+FF0D.
            if (code_point === 0x2212) code_point = 0xff0d

            // 9. Let pointer be the index pointer for code point in index
            // jis0208.
            var pointer = indexPointerFor(code_point, index("jis0208"))

            // 10. If pointer is null, return error with code point.
            if (pointer === null) return encoderError(code_point)

            // 11. If iso-2022-jp encoder state is not jis0208, prepend code
            // point to stream, set iso-2022-jp encoder state to jis0208,
            // and return three bytes 0x1B 0x24 0x42.
            if (iso2022jp_state !== states.jis0208) {
                stream.prepend(code_point)
                iso2022jp_state = states.jis0208
                return [0x1b, 0x24, 0x42]
            }

            // 12. Let lead be floor(pointer / 94) + 0x21.
            var lead = floor(pointer / 94) + 0x21

            // 13. Let trail be pointer % 94 + 0x21.
            var trail = (pointer % 94) + 0x21

            // 14. Return two bytes whose values are lead and trail.
            return [lead, trail]
        }
    }

    /** @param {{fatal: boolean}} options */
    encoders["ISO-2022-JP"] = function (options) {
        return new ISO2022JPEncoder(options)
    }
    /** @param {{fatal: boolean}} options */
    decoders["ISO-2022-JP"] = function (options) {
        return new ISO2022JPDecoder(options)
    }

    // 13.3 Shift_JIS

    // 13.3.1 Shift_JIS decoder
    /**
     * @constructor
     * @implements {Decoder}
     * @param {{fatal: boolean}} options
     */
    function ShiftJISDecoder(options) {
        var fatal = options.fatal
        // Shift_JIS's decoder has an associated Shift_JIS lead (initially
        // 0x00).
        var /** @type {number} */ Shift_JIS_lead = 0x00
        /**
         * @param {Stream} stream The stream of bytes being decoded.
         * @param {number} bite The next byte read from the stream.
         * @return {?(number|!Array.<number>)} The next code point(s)
         *     decoded, or null if not enough data exists in the input
         *     stream to decode a complete code point.
         */
        this.handler = function (stream, bite) {
            // 1. If byte is end-of-stream and Shift_JIS lead is not 0x00,
            // set Shift_JIS lead to 0x00 and return error.
            if (bite === end_of_stream && Shift_JIS_lead !== 0x00) {
                Shift_JIS_lead = 0x00
                return decoderError(fatal)
            }

            // 2. If byte is end-of-stream and Shift_JIS lead is 0x00,
            // return finished.
            if (bite === end_of_stream && Shift_JIS_lead === 0x00) return finished

            // 3. If Shift_JIS lead is not 0x00, let lead be Shift_JIS lead,
            // let pointer be null, set Shift_JIS lead to 0x00, and then run
            // these substeps:
            if (Shift_JIS_lead !== 0x00) {
                var lead = Shift_JIS_lead
                var pointer = null
                Shift_JIS_lead = 0x00

                // 1. Let offset be 0x40, if byte is less than 0x7F, and 0x41
                // otherwise.
                var offset = bite < 0x7f ? 0x40 : 0x41

                // 2. Let lead offset be 0x81, if lead is less than 0xA0, and
                // 0xC1 otherwise.
                var lead_offset = lead < 0xa0 ? 0x81 : 0xc1

                // 3. If byte is in the range 0x40 to 0x7E, inclusive, or 0x80
                // to 0xFC, inclusive, set pointer to (lead − lead offset) ×
                // 188 + byte − offset.
                if (inRange(bite, 0x40, 0x7e) || inRange(bite, 0x80, 0xfc))
                    pointer = (lead - lead_offset) * 188 + bite - offset

                // 4. If pointer is in the range 8836 to 10715, inclusive,
                // return a code point whose value is 0xE000 − 8836 + pointer.
                if (inRange(pointer, 8836, 10715)) return 0xe000 - 8836 + pointer

                // 5. Let code point be null, if pointer is null, and the
                // index code point for pointer in index jis0208 otherwise.
                var code_point = pointer === null ? null : indexCodePointFor(pointer, index("jis0208"))

                // 6. If code point is null and byte is an ASCII byte, prepend
                // byte to stream.
                if (code_point === null && isASCIIByte(bite)) stream.prepend(bite)

                // 7. If code point is null, return error.
                if (code_point === null) return decoderError(fatal)

                // 8. Return a code point whose value is code point.
                return code_point
            }

            // 4. If byte is an ASCII byte or 0x80, return a code point
            // whose value is byte.
            if (isASCIIByte(bite) || bite === 0x80) return bite

            // 5. If byte is in the range 0xA1 to 0xDF, inclusive, return a
            // code point whose value is 0xFF61 − 0xA1 + byte.
            if (inRange(bite, 0xa1, 0xdf)) return 0xff61 - 0xa1 + bite

            // 6. If byte is in the range 0x81 to 0x9F, inclusive, or 0xE0
            // to 0xFC, inclusive, set Shift_JIS lead to byte and return
            // continue.
            if (inRange(bite, 0x81, 0x9f) || inRange(bite, 0xe0, 0xfc)) {
                Shift_JIS_lead = bite
                return null
            }

            // 7. Return error.
            return decoderError(fatal)
        }
    }

    // 13.3.2 Shift_JIS encoder
    /**
     * @constructor
     * @implements {Encoder}
     * @param {{fatal: boolean}} options
     */
    function ShiftJISEncoder(options) {
        var fatal = options.fatal
        /**
         * @param {Stream} stream Input stream.
         * @param {number} code_point Next code point read from the stream.
         * @return {(number|!Array.<number>)} Byte(s) to emit.
         */
        this.handler = function (stream, code_point) {
            // 1. If code point is end-of-stream, return finished.
            if (code_point === end_of_stream) return finished

            // 2. If code point is an ASCII code point or U+0080, return a
            // byte whose value is code point.
            if (isASCIICodePoint(code_point) || code_point === 0x0080) return code_point

            // 3. If code point is U+00A5, return byte 0x5C.
            if (code_point === 0x00a5) return 0x5c

            // 4. If code point is U+203E, return byte 0x7E.
            if (code_point === 0x203e) return 0x7e

            // 5. If code point is in the range U+FF61 to U+FF9F, inclusive,
            // return a byte whose value is code point − 0xFF61 + 0xA1.
            if (inRange(code_point, 0xff61, 0xff9f)) return code_point - 0xff61 + 0xa1

            // 6. If code point is U+2212, set it to U+FF0D.
            if (code_point === 0x2212) code_point = 0xff0d

            // 7. Let pointer be the index Shift_JIS pointer for code point.
            var pointer = indexShiftJISPointerFor(code_point)

            // 8. If pointer is null, return error with code point.
            if (pointer === null) return encoderError(code_point)

            // 9. Let lead be floor(pointer / 188).
            var lead = floor(pointer / 188)

            // 10. Let lead offset be 0x81, if lead is less than 0x1F, and
            // 0xC1 otherwise.
            var lead_offset = lead < 0x1f ? 0x81 : 0xc1

            // 11. Let trail be pointer % 188.
            var trail = pointer % 188

            // 12. Let offset be 0x40, if trail is less than 0x3F, and 0x41
            // otherwise.
            var offset = trail < 0x3f ? 0x40 : 0x41

            // 13. Return two bytes whose values are lead + lead offset and
            // trail + offset.
            return [lead + lead_offset, trail + offset]
        }
    }

    /** @param {{fatal: boolean}} options */
    encoders["Shift_JIS"] = function (options) {
        return new ShiftJISEncoder(options)
    }
    /** @param {{fatal: boolean}} options */
    decoders["Shift_JIS"] = function (options) {
        return new ShiftJISDecoder(options)
    }

    //
    // 14. Legacy multi-byte Korean encodings
    //

    // 14.1 euc-kr

    // 14.1.1 euc-kr decoder
    /**
     * @constructor
     * @implements {Decoder}
     * @param {{fatal: boolean}} options
     */
    function EUCKRDecoder(options) {
        var fatal = options.fatal

        // euc-kr's decoder has an associated euc-kr lead (initially 0x00).
        var /** @type {number} */ euckr_lead = 0x00
        /**
         * @param {Stream} stream The stream of bytes being decoded.
         * @param {number} bite The next byte read from the stream.
         * @return {?(number|!Array.<number>)} The next code point(s)
         *     decoded, or null if not enough data exists in the input
         *     stream to decode a complete code point.
         */
        this.handler = function (stream, bite) {
            // 1. If byte is end-of-stream and euc-kr lead is not 0x00, set
            // euc-kr lead to 0x00 and return error.
            if (bite === end_of_stream && euckr_lead !== 0) {
                euckr_lead = 0x00
                return decoderError(fatal)
            }

            // 2. If byte is end-of-stream and euc-kr lead is 0x00, return
            // finished.
            if (bite === end_of_stream && euckr_lead === 0) return finished

            // 3. If euc-kr lead is not 0x00, let lead be euc-kr lead, let
            // pointer be null, set euc-kr lead to 0x00, and then run these
            // substeps:
            if (euckr_lead !== 0x00) {
                var lead = euckr_lead
                var pointer = null
                euckr_lead = 0x00

                // 1. If byte is in the range 0x41 to 0xFE, inclusive, set
                // pointer to (lead − 0x81) × 190 + (byte − 0x41).
                if (inRange(bite, 0x41, 0xfe)) pointer = (lead - 0x81) * 190 + (bite - 0x41)

                // 2. Let code point be null, if pointer is null, and the
                // index code point for pointer in index euc-kr otherwise.
                var code_point = pointer === null ? null : indexCodePointFor(pointer, index("euc-kr"))

                // 3. If code point is null and byte is an ASCII byte, prepend
                // byte to stream.
                if (pointer === null && isASCIIByte(bite)) stream.prepend(bite)

                // 4. If code point is null, return error.
                if (code_point === null) return decoderError(fatal)

                // 5. Return a code point whose value is code point.
                return code_point
            }

            // 4. If byte is an ASCII byte, return a code point whose value
            // is byte.
            if (isASCIIByte(bite)) return bite

            // 5. If byte is in the range 0x81 to 0xFE, inclusive, set
            // euc-kr lead to byte and return continue.
            if (inRange(bite, 0x81, 0xfe)) {
                euckr_lead = bite
                return null
            }

            // 6. Return error.
            return decoderError(fatal)
        }
    }

    // 14.1.2 euc-kr encoder
    /**
     * @constructor
     * @implements {Encoder}
     * @param {{fatal: boolean}} options
     */
    function EUCKREncoder(options) {
        var fatal = options.fatal
        /**
         * @param {Stream} stream Input stream.
         * @param {number} code_point Next code point read from the stream.
         * @return {(number|!Array.<number>)} Byte(s) to emit.
         */
        this.handler = function (stream, code_point) {
            // 1. If code point is end-of-stream, return finished.
            if (code_point === end_of_stream) return finished

            // 2. If code point is an ASCII code point, return a byte whose
            // value is code point.
            if (isASCIICodePoint(code_point)) return code_point

            // 3. Let pointer be the index pointer for code point in index
            // euc-kr.
            var pointer = indexPointerFor(code_point, index("euc-kr"))

            // 4. If pointer is null, return error with code point.
            if (pointer === null) return encoderError(code_point)

            // 5. Let lead be floor(pointer / 190) + 0x81.
            var lead = floor(pointer / 190) + 0x81

            // 6. Let trail be pointer % 190 + 0x41.
            var trail = (pointer % 190) + 0x41

            // 7. Return two bytes whose values are lead and trail.
            return [lead, trail]
        }
    }

    /** @param {{fatal: boolean}} options */
    encoders["EUC-KR"] = function (options) {
        return new EUCKREncoder(options)
    }
    /** @param {{fatal: boolean}} options */
    decoders["EUC-KR"] = function (options) {
        return new EUCKRDecoder(options)
    }

    //
    // 15. Legacy miscellaneous encodings
    //

    // 15.1 replacement

    // Not needed - API throws RangeError

    // 15.2 Common infrastructure for utf-16be and utf-16le

    /**
     * @param {number} code_unit
     * @param {boolean} utf16be
     * @return {!Array.<number>} bytes
     */
    function convertCodeUnitToBytes(code_unit, utf16be) {
        // 1. Let byte1 be code unit >> 8.
        var byte1 = code_unit >> 8

        // 2. Let byte2 be code unit & 0x00FF.
        var byte2 = code_unit & 0x00ff

        // 3. Then return the bytes in order:
        // utf-16be flag is set: byte1, then byte2.
        if (utf16be) return [byte1, byte2]
        // utf-16be flag is unset: byte2, then byte1.
        return [byte2, byte1]
    }

    // 15.2.1 shared utf-16 decoder
    /**
     * @constructor
     * @implements {Decoder}
     * @param {boolean} utf16_be True if big-endian, false if little-endian.
     * @param {{fatal: boolean}} options
     */
    function UTF16Decoder(utf16_be, options) {
        var fatal = options.fatal
        var /** @type {?number} */ utf16_lead_byte = null,
            /** @type {?number} */ utf16_lead_surrogate = null
        /**
         * @param {Stream} stream The stream of bytes being decoded.
         * @param {number} bite The next byte read from the stream.
         * @return {?(number|!Array.<number>)} The next code point(s)
         *     decoded, or null if not enough data exists in the input
         *     stream to decode a complete code point.
         */
        this.handler = function (stream, bite) {
            // 1. If byte is end-of-stream and either utf-16 lead byte or
            // utf-16 lead surrogate is not null, set utf-16 lead byte and
            // utf-16 lead surrogate to null, and return error.
            if (bite === end_of_stream && (utf16_lead_byte !== null || utf16_lead_surrogate !== null)) {
                return decoderError(fatal)
            }

            // 2. If byte is end-of-stream and utf-16 lead byte and utf-16
            // lead surrogate are null, return finished.
            if (bite === end_of_stream && utf16_lead_byte === null && utf16_lead_surrogate === null) {
                return finished
            }

            // 3. If utf-16 lead byte is null, set utf-16 lead byte to byte
            // and return continue.
            if (utf16_lead_byte === null) {
                utf16_lead_byte = bite
                return null
            }

            // 4. Let code unit be the result of:
            var code_unit
            if (utf16_be) {
                // utf-16be decoder flag is set
                //   (utf-16 lead byte << 8) + byte.
                code_unit = (utf16_lead_byte << 8) + bite
            } else {
                // utf-16be decoder flag is unset
                //   (byte << 8) + utf-16 lead byte.
                code_unit = (bite << 8) + utf16_lead_byte
            }
            // Then set utf-16 lead byte to null.
            utf16_lead_byte = null

            // 5. If utf-16 lead surrogate is not null, let lead surrogate
            // be utf-16 lead surrogate, set utf-16 lead surrogate to null,
            // and then run these substeps:
            if (utf16_lead_surrogate !== null) {
                var lead_surrogate = utf16_lead_surrogate
                utf16_lead_surrogate = null

                // 1. If code unit is in the range U+DC00 to U+DFFF,
                // inclusive, return a code point whose value is 0x10000 +
                // ((lead surrogate − 0xD800) << 10) + (code unit − 0xDC00).
                if (inRange(code_unit, 0xdc00, 0xdfff)) {
                    return 0x10000 + (lead_surrogate - 0xd800) * 0x400 + (code_unit - 0xdc00)
                }

                // 2. Prepend the sequence resulting of converting code unit
                // to bytes using utf-16be decoder flag to stream and return
                // error.
                stream.prepend(convertCodeUnitToBytes(code_unit, utf16_be))
                return decoderError(fatal)
            }

            // 6. If code unit is in the range U+D800 to U+DBFF, inclusive,
            // set utf-16 lead surrogate to code unit and return continue.
            if (inRange(code_unit, 0xd800, 0xdbff)) {
                utf16_lead_surrogate = code_unit
                return null
            }

            // 7. If code unit is in the range U+DC00 to U+DFFF, inclusive,
            // return error.
            if (inRange(code_unit, 0xdc00, 0xdfff)) return decoderError(fatal)

            // 8. Return code point code unit.
            return code_unit
        }
    }

    // 15.2.2 shared utf-16 encoder
    /**
     * @constructor
     * @implements {Encoder}
     * @param {boolean} utf16_be True if big-endian, false if little-endian.
     * @param {{fatal: boolean}} options
     */
    function UTF16Encoder(utf16_be, options) {
        var fatal = options.fatal
        /**
         * @param {Stream} stream Input stream.
         * @param {number} code_point Next code point read from the stream.
         * @return {(number|!Array.<number>)} Byte(s) to emit.
         */
        this.handler = function (stream, code_point) {
            // 1. If code point is end-of-stream, return finished.
            if (code_point === end_of_stream) return finished

            // 2. If code point is in the range U+0000 to U+FFFF, inclusive,
            // return the sequence resulting of converting code point to
            // bytes using utf-16be encoder flag.
            if (inRange(code_point, 0x0000, 0xffff)) return convertCodeUnitToBytes(code_point, utf16_be)

            // 3. Let lead be ((code point − 0x10000) >> 10) + 0xD800,
            // converted to bytes using utf-16be encoder flag.
            var lead = convertCodeUnitToBytes(((code_point - 0x10000) >> 10) + 0xd800, utf16_be)

            // 4. Let trail be ((code point − 0x10000) & 0x3FF) + 0xDC00,
            // converted to bytes using utf-16be encoder flag.
            var trail = convertCodeUnitToBytes(((code_point - 0x10000) & 0x3ff) + 0xdc00, utf16_be)

            // 5. Return a byte sequence of lead followed by trail.
            return lead.concat(trail)
        }
    }

    // 15.3 utf-16be
    // 15.3.1 utf-16be decoder
    /** @param {{fatal: boolean}} options */
    encoders["UTF-16BE"] = function (options) {
        return new UTF16Encoder(true, options)
    }
    // 15.3.2 utf-16be encoder
    /** @param {{fatal: boolean}} options */
    decoders["UTF-16BE"] = function (options) {
        return new UTF16Decoder(true, options)
    }

    // 15.4 utf-16le
    // 15.4.1 utf-16le decoder
    /** @param {{fatal: boolean}} options */
    encoders["UTF-16LE"] = function (options) {
        return new UTF16Encoder(false, options)
    }
    // 15.4.2 utf-16le encoder
    /** @param {{fatal: boolean}} options */
    decoders["UTF-16LE"] = function (options) {
        return new UTF16Decoder(false, options)
    }

    // 15.5 x-user-defined

    // 15.5.1 x-user-defined decoder
    /**
     * @constructor
     * @implements {Decoder}
     * @param {{fatal: boolean}} options
     */
    function XUserDefinedDecoder(options) {
        var fatal = options.fatal
        /**
         * @param {Stream} stream The stream of bytes being decoded.
         * @param {number} bite The next byte read from the stream.
         * @return {?(number|!Array.<number>)} The next code point(s)
         *     decoded, or null if not enough data exists in the input
         *     stream to decode a complete code point.
         */
        this.handler = function (stream, bite) {
            // 1. If byte is end-of-stream, return finished.
            if (bite === end_of_stream) return finished

            // 2. If byte is an ASCII byte, return a code point whose value
            // is byte.
            if (isASCIIByte(bite)) return bite

            // 3. Return a code point whose value is 0xF780 + byte − 0x80.
            return 0xf780 + bite - 0x80
        }
    }

    // 15.5.2 x-user-defined encoder
    /**
     * @constructor
     * @implements {Encoder}
     * @param {{fatal: boolean}} options
     */
    function XUserDefinedEncoder(options) {
        var fatal = options.fatal
        /**
         * @param {Stream} stream Input stream.
         * @param {number} code_point Next code point read from the stream.
         * @return {(number|!Array.<number>)} Byte(s) to emit.
         */
        this.handler = function (stream, code_point) {
            // 1.If code point is end-of-stream, return finished.
            if (code_point === end_of_stream) return finished

            // 2. If code point is an ASCII code point, return a byte whose
            // value is code point.
            if (isASCIICodePoint(code_point)) return code_point

            // 3. If code point is in the range U+F780 to U+F7FF, inclusive,
            // return a byte whose value is code point − 0xF780 + 0x80.
            if (inRange(code_point, 0xf780, 0xf7ff)) return code_point - 0xf780 + 0x80

            // 4. Return error with code point.
            return encoderError(code_point)
        }
    }

    /** @param {{fatal: boolean}} options */
    encoders["x-user-defined"] = function (options) {
        return new XUserDefinedEncoder(options)
    }
    /** @param {{fatal: boolean}} options */
    decoders["x-user-defined"] = function (options) {
        return new XUserDefinedDecoder(options)
    }

    if (!global["TextEncoder"]) global["TextEncoder"] = TextEncoder
    if (!global["TextDecoder"]) global["TextDecoder"] = TextDecoder

    if (typeof module !== "undefined" && module.exports) {
        module.exports = {
            TextEncoder: global["TextEncoder"],
            TextDecoder: global["TextDecoder"],
            EncodingIndexes: global["encoding-indexes"],
        }
    }

    // For strict environments where `this` inside the global scope
    // is `undefined`, take a pure object instead
})(this || {})
